L-Theanine, derived naturally from the leaves of the Camellia sinensis plant, is a psychoactive glutamate analog. It has been studied as a possible complementary treatment for anxiety, stress, depression and hypertension. However, L-Theanine is not approved by the FDA for the treatment of any condition. You should talk with your doctor before taking any supplement that contains L-theanine.
Pharmacology
Much of L-theanine's pharmacological activity is thought to be the product of its action on the body's inhibitory neurochemical pathway GABA. Valium and other benzodiazepine medications make use of this pathway to treat anxiety, as does L-theanine, which may make it useful in the treatment of psychogenic hypertension. Additionally, L-theanine may affect the level of serotonin, a neurotransmitter responsible for regulating both mood and blood pressure.
Research
In 1999, a study by researchers at the University of Shizuoka in Japan, published in "Trends in Food Science and Technology" found that L-theanine had statistically significant anti-hypertensive properties. The Department of Experimental Psychology at the University of Bristol in 2008 wrote in a paper published in "Psychopharmacology" that L-theanine helped to counteract the blood pressure elevating properties of caffeine.
Interactions and Contraindications
L-Theanine is not believed to cause any adverse reactions when taken alongside any herbs, supplements or medications, according to Drugs.com, nor are there any reported contraindications. It would be sensible to assume that L-theanine would enhance the effects of drugs that treat anxiety or high blood pressure, but no interactions with these drugs have been reported. The U.S. Food and Drug Administration, while making no claims as to the efficacy of L-theanine in the treatment of hypertension, classifies L-theanine supplements as "Generally Recognized As Safe."
Side-Effects
The incidence of side-effects with L-theanine supplementation is low. Some people experience headaches. Infrequently, some patients also experience gastrointestinal upset or dizziness. No long-term studies have yet been done on the effects of L-theanine at therapeutic doses, however. Consequently, it is impossible to conclusively say that the use of high doses of L-theanine over a long time is safe.
References
- "Psychopharmacology"; Time for Tea: Mood, Blood Pressure and Cognitive Performance Effects of Caffeine and Theanine Administered Alone and Together; P.J. Rogers, et al; June 2008
- "Trends in Food Science and Technology"; Review: L-Theanine---A Unique Amino Acid of Green Tea and its Relaxation Effect in Humans; L.R. Juneja, et al; June 1999
- Reduction Effect of Theanine on Blood Pressure and Brain 5-Hydroxyindoles in Spontaneous Hypertensive Rats; Hidehiko Yokogoshi; 1995
- "Biological Psychology"; L-Theanine Reduces Psychological and Physiological Stress Responses; K. Kimura, et al; January 2007
- "Biological Psychology"; The Effects of L-Theanine, Caffeine and Their Combination on Cognition and Mood; C.F. Haskell, et al; February 2008
- "Journal of Clinical Psychiatry"; L-Theanine Relieves Positive, Activation, and Anxiety Symptoms in Patients with Schizophrenia and Schizoaffective Disorder: An 8-Week, Randomized, Double-Blind, Placebo-Controlled, 2-Center Study; M.S. Ritsner, et al; 2010
